Morphologic Features and Clinical Outcomes of Acinar Cell Carcinoma of the Pancreas: A Multicenter Retrospective Study of 37 Patients in South Korea.

Background: The clinical characteristics of pancreatic acinar cell carcinoma (ACC) remain poorly defined due to its rarity. This study aimed to evaluate the morphological features and clinical outcomes of pancreatic ACC. Method: This multicenter retrospective study analyzed clinical data from seven referral hospitals. Electronic medical records were comprehensively reviewed to extract patient data. Survival outcomes were calculated from the date of pathologic confirmation of ACC. Results: Of the 37 patients, 28 (75.7%) were male. The age distribution at diagnosis ranged widely from 12 to 86 years, with a median of 62.0 years; seven patients (18.9%) were aged under 50 years. Morphologically, 24 patients (64.9%) presented with solid masses, whereas four had cystic masses and four exhibited mixed solid and cystic components. Regarding tumor resectability, 19 patients (51.4%) had resectable disease, 7 (18.9%) were locally advanced, and 11 (29.7%) were metastatic. In terms of treatment, 22 patients (59.4%) underwent surgical resection, 12 (32.4%) received palliative chemotherapy, and the remainder received best supportive care. In the surgical resection group, the median OS was not reached, demonstrating significantly prolonged survival (mean OS, 7.6 years; 5-year OS rate, 51%). In contrast, the median OS was 0.9 years in the palliative chemotherapy group and 0.1 years in the best supportive care group (p = 0.040). Conclusions: Pancreatic ACC showed a broad age distribution, with approximately 20% of patients aged <50 years, and pleomorphic morphological features, including solid, cystic, and mixed patterns. Patients who underwent surgical resection demonstrated favorable long-term survival outcomes compared to historical data for pancreatic ductal adenocarcinoma.